left brake hangs when hot

[Paul Klouda]

Greetings All,

During my last annual '64 PA-24 I replaced brake pads, rebuilt master cylinders (leaking a bit from seals) and flushed, replaced and bled brake fluid. My left brake is hanging up intermittently (grabbing and not releasing) when it gets hot. We pulled the brake assy (Cleveland Brakes) checked the pads, piston, cylinder etc and everything appears to be free and per guide.

Thinking about pulling the left master again and checking the rebuild?

Not sure what else to look for, but when it hangs it is a beast to move!

I'm open to suggestions.

Thanks in advance.

Paul

[Zach Grant L1011jock]

It is most probably you parking brake valve on the top of the master cylinder. I tell people not to use the parking brake on these as these valves are the Achilles heal of both brake failure, as well as brake lockup, and they can and have caused significant damage from unexpected turning tendencies on touchdown. The diagram of the system is in the parts book, and all the o rings and seals are ms STD stuff. I suggest you get it fixed before further flight.

Zach

[Paul Klouda]

Thank you Zach, will do! BTW I have not used the parking brake since owning the plane, I did hear it causes more problems than its worth. I made a pair of wheel chocks in lieu of using the parking brake. The wild card here is during reassembly of the master cylinders something may have happened.

Regards,

Paul

[MULEFLY]

Paul --

As Zach knows, I've gone thru 4 sets of brakes on my twinco in the last 35 hours... discs and pads! But I think (knock on wood) that we have it solved for now... we have changed so much, I can't really pin it down on anything... but one issue early on that was overlooked for a bit was the torque plates -- they were bent, causing the pins not to be in perfect alignment.

Cleveland is also emphatic that the bolts holding the caliper assemblies together not be torqued more than about 65 IN POUNDS... I'll bet that I could check 100 Comanches and find that these bolts are in an overtorqued condition.

There is a 4 page excerpt from Clevelands Troubleshooting guide Manual AWBCMM0001-7/USA that you may find helpful. If you do not have it... pvt email me jim dot covington at inwave dot com and I'll forward you a PDF file.

Final hint... I'm never putting anything but Cleveland discs and pads on my airplane again...

All the best!
Jim